It is Chairman Richard Neal’s (D-Mass.) responsibility to ensure that they appear before the committee and address the mounting concerns surrounding the Treasury Department’s involvement in legally questionable maneuvers to lessen costly political backlash to the ongoing shutdown.

Charles Rettig, the Internal Revenue Service (IRS) commissioner, is claiming to be too busy running his unfunded and somewhat dormant agency to show up Jan. 16 to a scheduled meeting with the House Committee on Ways and Means where he was to brief members on the shutdown’s impacts on taxpayers. There is no word yet if Rettig has agreed to a new meeting date.

Following this cancellation, Chairman Neal, to his credit, did not fold. Instead, he escalated the complaint and announced that the committee would hold a hearing next week on the same topic, this time inviting Treasury Secretary Steven Mnuchin to testify. Mnuchin declined, offering to send deputies instead.

What is keeping these two officials from fulfilling requests from a committee that could issue a subpoena? Our best guess is that neither official wants to defend certain legally questionable actions that the Treasury Department has taken in the nearly two weeks since Neal first requested a briefing.

Equally important, it is clear that neither Rettig nor Mnuchin has any fear of repercussions from the chair of the once powerful Ways and Means Committee.

Neal’s ability to credibly threaten that he might issue a subpoena has been undercut by his feckless refusal to follow through on commitments by himself and the Democratic Party’s leadership to request Trump’s tax returns upon taking control of the House.

Politico explained Neal’s hesitancy to request Trump’s tax returns, writing that “going to war with the administration over the issue threatens their chances of working together on other, substantial tax issues.”

Yet, it is clear that Neal’s weakness concerning Trump’s tax returns is not promoting useful collaboration but is instead signaling weakness to Trump.

As we wrote in The American Prospect, failing to move expeditiously to review Trump’s tax returns and determine to whom his economic loyalties are owed is bad not only in and of itself but for what it portends about how the Ways and Means Committee will execute its potentially vast oversight authority.

That senior Treasury Department officials view Neal and the Ways and Means Committee — historically perhaps the most powerful committee in all of Congress — as so ineffectual that they can blow off meetings and flat out refuse invitations is revelatory.

A little background: From the shutdown’s start, the Trump administration has broken with precedent and potentially crossed legal boundaries to quieten political backlash against what Trump himself termed “the Trump shutdown.”

For example, the administration decided not to close national parks, but instead leave them open and severely understaffed, leading to unsafe and unsanitary conditions.

At the same time, the administration has been faithfully fulfilling requests from moneyed interests to resume certain governmental functions and bypass others.

As discontent over the shutdown has mounted, the administration has expanded its efforts to minimize negative impacts that might exacerbate the political cost the shutdown is imposing on Trump.

While dampening the shutdown’s impacts may appear a noble goal on its surface, the administration’s actions are legally dubious. Moreover, these half-measures distract from the most direct and effective path to alleviating shutdown-related pain — reopening the government along the lines of a bill which passed the Senate unanimously last month.

This brings us back to Rettig and Mnuchin. The Treasury Department is presently leading the administration’s most brazen attempt to reduce political backlash and likely does not want to answer for its actions in Congress. Neither official, however, should be allowed to avoid that confrontation.

Over 800,000 workers have gone a full month without pay. Any effort by the Trump administration to prolong this crisis, especially by legally questionable means, should come under investigation. The American people deserve answers now.

Neal’s chairmanship is only three weeks old. He has time to change course and deploy his potentially powerful committee as an institution committed to economic justice and the equality under the law.

But, until Chairman Neal demonstrates a commitment to oversight, the Trump administration will walk all over him and the interests of working people.

Jeff Hauser is the director of the Revolving Door Project, which aims to increase scrutiny on executive branch appointments, at the Center for Economic and Policy Research.